Reflective Filter for Pyrometry in Rapid Thermal Processing
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Solution Overview
Problem
In rapid thermal processing of semiconductor substrates, accurate temperature measurement is hindered by interference from radiation originating from the heat source, particularly at lower temperatures where the substrate is transparent to this radiation, affecting the reliability of pyrometer readings.
Innovation Solution
A system with a window separating the heat source and substrate, featuring a reflective layer that prevents radiation within specific wavelengths from reaching the pyrometer, ensuring accurate temperature measurement by reflecting source radiation back towards the heat source and allowing only substrate radiation to be detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pyrometer is used to measure substrate temperature, then temperature measurement capability is provided, but measurement precision deteriorates due to heat source radiation interference
Solution Approach 1:
A reflective filter is introduced as an intermediary component between the heat source and the pyrometer. This filter selectively reflects radiation within the pyrometer's detection bandwidth back toward the heat source, while allowing radiation from the substrate to reach the pyrometer. The filter acts as a mediator that separates the harmful heat source radiation from the useful substrate radiation signals.
Solution Approach 2:
The reflective filter is positioned specifically at the location where it can intercept heat source radiation before it reaches the pyrometer, while maintaining transparency to substrate radiation. The filter's reflective properties are applied locally to the specific wavelength range detected by the pyrometer, creating a localized solution that addresses the interference problem without affecting other parts of the system.
2Use of energy by moving object
If the substrate is at lower temperature, then energy consumption is reduced, but measurement precision deteriorates because the substrate becomes transparent to pyrometer radiation
Solution Approach 1:
The reflective filter serves as a mediator that compensates for the substrate's transparency at lower temperatures. By blocking heat source radiation in the pyrometer's detection band, the filter ensures that the pyrometer measures only substrate radiation, even when the substrate is transparent at these temperatures and lower energy consumption conditions.
3Productivity
If rapid thermal processing is performed, then productivity is improved, but measurement precision deteriorates due to transient temperature conditions
Solution Approach 1:
The reflective filter provides continuous discrimination between heat source and substrate radiation throughout the rapid thermal processing cycle. During transient heating and cooling phases, the filter ensures that the pyrometer consistently measures only substrate radiation, maintaining measurement precision despite the dynamic and rapidly changing temperature conditions characteristic of high-productivity RTP processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the accuracy of temperature measurements in rapid thermal processing by minimizing interference from heat source radiation, particularly at lower temperatures, thereby improving the precision of pyrometry in semiconductor processing.
Implementation Method 1
a reflective layer placed on the side of the window facing the heat source and covering an entire surface between the heat source and the substrate, the reflective layer being substantially reflective to radiation in the second range of wavelengths
Implementation Method 2
the window being made from a material which is substantially transparent to radiation in the first range of wavelengths and having a reflective layer placed on the side of the window facing the heat source
Implementation Method 3
a pyrometer for measuring the temperature of the substrate disposed within a process area of the chamber by detecting radiation in a second range of wavelengths within the first range of wavelengths
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Methods and apparatus for processing substrates and measuring the temperature using radiation pyrometry are disclosed. A reflective layer is provided on a window of a processing chamber. A radiation source providing radiation in a first range of wavelengths heats the substrate, the substrate being transparent to radiation in a second range of wavelengths within the first range of wavelengths for a predetermined temperature range. Radiation within the second range of wavelength is reflected by the reflective layer.